Mammal Society marks start of ‘harvest mouse survey season’ with an urgent appeal for volunteers, and announcement of the UK’s first ever ‘National Harvest Mouse Day’ on 19th October - Mammal Society

• The fourth survey season of the National Harvest Mouse Survey runs from 1st October 2025 to 31st March 2026. Volunteers search for the now empty nests of harvest mice in long grass and reeds to confirm presence.

• Volunteer participation in the survey dropped last year, and the charity is putting out an urgent appeal for surveyors to help – especially in areas of the country that currently have no survey data.

• Surveying is fun and easy with no qualifications required. Families, schools and youth groups can get involved.

• To build awareness of the importance of the harvest mouse and this survey, the Mammal Society has launched a National Harvest Mouse Day on 19th October, and hopes people will mark it by learning about this amazing animal and getting out into their local landscape to survey for nests.

October marks the start of the survey season for the National Harvest Mouse Survey, run by the Mammal Society – the only UK charity dedicated to the study and conservation of all native mammals.

Throughout the Autumn and Winter, volunteers will brave the cold to search fields, reed beds and hedgerows across England, Wales and Scotland for the distinctive spherical nests woven from grass that will now have been vacated by the mother and newly weaned pups.

The survey launched in 2021 in response to the findings of the Mammal Society’s review of the population and conservation status of British mammals (Mathews et al. 2018), which revealed that the conservation status of the smallest British rodent could not be determined due to a lack of robust data.

Monitoring small mammals such as mice, shrews and voles is difficult and time-intensive due to their diminutive size, fluctuating local populations, and elusiveness. However small mammals are essential to healthy ecosystems, due to their role in forming and maintaining healthy and well drained soil, seed dispersal, keeping insect populations in balance, and their vital importance as prey for raptors and larger mammals. Harvest mice are Britain’s smallest rodent, and the only native mammal to have a prehensile tail (meaning they can use it as a limb to hold on to branches when climbing). There is evidence that harvest mice are indicators of healthy ecosystems, meaning that data on their presence is important to guide conservation and land management decisions.